STS-122 (1E) Updates

tanstaafl76 · Dec 13, 2007

Interesting article found here: http://www.spaceref.com/news/viewnews.html?id=1255 Internal NASA emails from the director of Shuttle Safety at the Johnson Space Center and the Shuttle Program Manager show how they struggled with the potential risk to astronauts' lives in assessing how to proceed with the launch of Atlantis in the wake of engine cutoff (ECO) sensor malfunctions. Aviation Week & Space Technology obtained copies of these emails, which are reproduced largely in full here on AviationWeek.com to retain the context intended by their authors. The emails were sent to the team by astronaut Bill McArthur, Jr. who heads the Space Shuttle Safety and Mission Assurance Office at the Johnson Space Center and Wayne Hale, shuttle program manager. McArthur has launched into space three times on the shuttle, a fourth time atop a Russian Soyuz and he also commanded the International Space Station. The emails were sent Dec. 7. This was a day after the Atlantis countdown was scrubbed Dec. 6 when two ECO sensors failed and managers debated whether they could proceed Dec. 8 or needed more time. They ultimately slipped the next attempt to Dec. 9 after setting new flight rules that 4 good ECO sensors would be required. This was a change to the original Atlantis launch rule that said the vehicle could fly with 3 of 4. The Dec. 9 attempt was then scrubbed when one ECO sensor failed in the countdown, a situation that two days before, would have been "go" for launch. The emails indicate that some of NASA's highest managers believe that the design of the total system would enable safe launch of the shuttle, without use of any ECO sensor system at all. It is designed to protect against an oxygen rich engine shutdown that would cause a catastrophic explosion. Hale cites past flight data that indicates <div class="Discussion_UserSignature"> </div>

MeteorWayne · Dec 13, 2007

A good summary (if clumsily worded) of the current (hahahaha) thinking. Thanx Wayne <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

MeteorWayne · Dec 13, 2007

An great summary of Wayne's thinking as this has evolved. Thanx to you too! <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

vulture2 · Dec 13, 2007

"Wouldn't it make more sense to determine if a sensor is really needed, and if so, to redesign it to be more reliable?" />>If this path is taken you might as well end the Shuttle program now. There is not enough time to do this. I thought the lesson of Challenger was that we should take the time to do the job right. Maybe doing the job right would be just deleting the sensor. But if it's needed, and it's not reliable, we should correct the problem first.

bpcooper · Dec 13, 2007

They have just announced January 10 at 2:26am EST as the new target launch date. <div class="Discussion_UserSignature"> -Ben </div>

MeteorWayne · Dec 13, 2007

Ooooh, cool, a night launch. I can see them form here. As long as the problem is fixed, that would be great <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

bobblebob · Dec 14, 2007

May have to take the day off work then <img src="/images/icons/laugh.gif" /> Although a long long way off a launch yet

MeteorWayne · Dec 15, 2007

Looks like I'll have a busy morning at the computer!! Thanx <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

bobblebob · Dec 15, 2007

Tanking test in on Nasa TV (media channel i believe) for people who didnt know

MeteorWayne · Dec 15, 2007

That's what s_g's last post was about. Dec. 14, 2007 Candrea Thomas Kennedy Space Center, Fla. 321-867-2468 candrea.k.thomas@nasa.gov STATUS REPORT: S-121407 NASA'S SPACE SHUTTLE PROCESSING STATUS REPORT Note: NASA's Kennedy Space Center issues Space Shuttle Processing Status Reports periodically and is the source for information regarding processing activities associated with the vehicles and payloads. Mission: STS-122 - 24th International Space Station Flight - Columbus Module Vehicle: Atlantis (OV-104) Location: Launch Pad 39A Launch Date: Targeted for Jan. 10, 2008 Crew: Frick, Poindexter, Schlegel, Eyharts, Love, Melvin, Walheim Inclination/Orbit Altitude: 51.6 degrees/122 nautical miles Shuttle Program managers decided Thursday to target Jan. 10, 2008, to launch the STS-122 mission. At Launch Pad 39A, preparations continue for a Dec. 18 tanking test to troubleshoot the engine cutoff (ECO) sensors. Test wiring has been spliced into an electrical harness in the aft main engine compartment connected with the ECO sensor system. The attached wiring leads to the interior of the mobile launcher platform where the time domain reflectometry (TDR) test equipment will be located. This wiring is being tested today. On Wednesday in the Vehicle Assembly Building, the TDR was connected to the external tank to be used for STS-123. This allowed a "dry" ambient temperature signature to be identified. Friday in Kennedy Space Center's cryogenic test bed facility, TDR instrumentation is being exposed to "wet" super-cold temperatures for identifying the signature of a cryogenic environment and calibrating the TDR equipment. Saturday, the TDR will be taken to the launch pad and installed. The GO2 battery recharge was completed and the GH2 <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

vulture2 · Dec 15, 2007

As I understand it, a time domain reflectometer evaluates the impedance along a transmission line; either it will show there is an abnormality in the line, or that there is no abnormality. If there is no abnormality, what caused the failure? How will the test allow a safe launch to proceed?

billslugg · Dec 16, 2007

vulture2 I know nothing about time domain reflectometry, but I do have an EE degree. If one was to generate a sufficiently short and powerful pulse and introduce it into a network, one could look at the reflected signal and see all kinds of good information. The best situation would be to look into a long wire, because then each time segment in the reflection can be traced to one particular spot on the wire. A two or three dimensional network would be nightmarish.There will also be second and third order reflections that must be sorted out but it can be done. The key, of course, is to see an anomaly. That could be an obvious short, short to ground, or open. One could also get a clean read from another orbiter (I believe they did 124 today) then one could see much more subtle differences. It is likely that the glitch will know when the analysts are coming and will exhibit best behavior. I could not tell you how many times I sat waiting only to have a glitch appear the minute I left for lunch. I came to refer to some gremlins by affectionate nicknames. I sometimes went into the plant at an unannounced time or came in a different door to surprise the gremlin. I never failed to get one however. Actually, I left a few there when I retired, but they were passed on to good people. What I meant to say was that I never gave up on one. I had some go out on a flatbed to the landfill and some that got sold to other companies, but I never surrendered to one. Sort of like some of the posters here at SDC. My longest duration gremlin introduced himself the day I joined the paper making group in 1976. I was not authorized to actually spend money working on it, since it was considered not solvable and was not in my work plan, but I chipped away at it for 13 years. I used scavenged parts, loaner equipment, funds from other sources, borrowed labor, arm twisting, and I even stepped on a few toes. But I finally got it. In 1989 I gave a presentation to the CEO of P <div class="Discussion_UserSignature"> </div>

MeteorWayne · Dec 16, 2007

The advantage of using the TDR (and you described the process very well) is that it can show very small anomoly's; much smaller than would be a functional fault. I believe I put it as shwing things that are just thinking about being faults. For example, it will clearly show the connector, even a perfect one. It will show a wire that's been squeezed, dented, or bent too sharply. So even before tanking, they will have a test of that condition, showing all of these things. Even if after tanking things are on their best behavior (ie.e no fault) the hope is the offending connection will show a large enough change in reflectivity to pinpoint the likely cause. <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

MeteorWayne · Dec 16, 2007

Or the "not quite open" <img src="/images/icons/smile.gif" /> I used to repair them back when I worked at Tektronix. <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

bobblebob · Dec 16, 2007

Whatever the tests reveal, is there any possibility of them not having to rollback to the VAB and can fix whatever problem they find at the pad?

MeteorWayne · Dec 16, 2007

From what Wayne said at the Press Conference, that is a possibility. Now s_g may know more than I, but it truly depends on what the problem they find is. <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

erioladastra · Dec 16, 2007

"Whatever the tests reveal, is there any possibility of them not having to rollback to the VAB and can fix whatever problem they find at the pad? " Or not fix at all - still developing procedures, rules, software, testing and simulating using alternate indications. If I were to bet I would say we are going Jan 10.

montmein69 · Dec 17, 2007

Or not fix at all - still developing procedures, rules, software, testing and simulating using alternate indications Is there another way to have an accurate knowledge of the low level of LH2 in the tank (and command a MECO in the required time for safety) than using the ECO sensors ? <div class="Discussion_UserSignature"> </div>

farmerman · Dec 17, 2007

Hey shuttle guy, what is your guess on what or where the problem is? From what I have been reading it's not the sensors themselves.

bobblebob · Dec 17, 2007

"NASA will hold a briefing no earlier than 4:30 p.m. EST, on Tuesday, Dec. 18, to discuss the results from a fueling test of the space shuttle Atlantis. "

earth_bound_misfit · Dec 18, 2007

"the failure mode has been that some will fail in about 30 min." Is that good or bad? <div class="Discussion_UserSignature"> ----------------------------------------------------------------- Wanna see this site looking like the old SDC uplink?Go here to see how: SDC Eye saver </div>

MeteorWayne · Dec 18, 2007

Actually, I'd say that's excellent! <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

MeteorWayne · Dec 18, 2007

Of course, ECO 1 was not one that failed before. Figures... Was that the only one? Still it points to that very busy connector as the problem. I'm trying to imagine what kind of a fix would be possible. One possibility might be to put a slight wrinkle in the pins, so that instead of being perfectly straight, they would have a bend in them. something like this, where the pin is the column of x's ...x.... ...x.... ...x.... ...x.... .....x.. ....x... ....x... ....x... That small offset might be enough to cause the thermal stresses to increase the contact at that point. I've often used that technique in resolving intermittents in my decades of electronic experience, though I don't often deal with cryo temps <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

montmein69 · Dec 18, 2007

Where is located this LH2 Feedthrough Connector ? Any way to modify/adapt it on the pad ? <div class="Discussion_UserSignature"> </div>

MeteorWayne · Dec 18, 2007

IIRC, it is where the wires pass through the outside of the LH2 tank. The sensors are inside the tank, the rest of the system (including wiring) is outside the tank. This is where the voltages pass through a connector, so that the electronics can be connected to the data from the sensors. <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

STS-122 (1E) Updates

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